1. Field of the Invention
This invention relates to a switching type continuously effective printing machine and a method of operating the same, which are applicable for shop name changes or the like in commercial printing of newspaper insert leaflets, direct mails, etc. with off-set rotary presses.
2. Description of the Related Art
Heretofore, in the commercial printing of newspaper insert leaflets and handbills, direct mails, catalogs, etc. with offset rotary presses, usually only character spot shop names, dates, prices, etc. are changed while leaving photographic processes or the like without alteration.
Such plate change printing is done by stopping the off-set rotary press, changing only the shop name plate, etc., and then operating the printing press again for duty service.
In addition to such plate change printing method, in which the off-set rotary press is once stopped, there is another plate change printing method, in which an in-printer (continuous printer) is connected to the off-set rotary press for carrying out the plate change printing without stopping the off-set rotary press. FIG. 6 shows an off-set rotary press 930, to which an in-printer 910 is connected.
Shown on the left side in the Figure is an in-feeder 902 for feeding out a continuous printing web 901. Shown on the right side of the Figure is a first color printing unit 931 of a multi-color off-set rotary press 930. An in-printer 910 is installed between the in-feeder 902 and the printing unit 931.
The in-printer 910 internally includes a common pressure cylinder 911, two printing cylinders 912 and 913 disposed above and below the pressure cylinder 911, and inking mechanisms 914 and 915 disposed above and below the plate cylinders 912 and 913 and each having a plurality of ink rollers rotated in contact with one another.
The printing plates of the plate cylinders 912 and 913 are flexographic plates (i.e., relief printing plates made of rubber, a resin, etc.). They are adapted to be secured by double-side adhesive tape, adhesive, etc. to the individual plate cylinders 912 and 913 at plate change positions thereof.
With such off-set rotary press 930 with the in-printer 910 connected thereto, the continuous printing web 901 fed from the in-feeder 902 is pinched between the common pressure cylinder 911 and one of the plate cylinders (for instance plate cylinder 912) for printing a shop name or the like.
During the printing with the printing cylinder 912, plate change of the other printing cylinder 913 is made to make the printing cylinder 913 ready for printing.
Subsequently, the printing cylinder 913 is started to switch the printing cylinders 913 and 912 and have the printing cylinder 913 in a printing state, while stopping the printing cylinder 912 for the next plate change.
After plate change Printing of a shop name or the like has been carded out with the in-printer 910 in this way, the continuous printing web is fed to the downstream off-set rotary press 930 for multi-color printing with plate cylinders 932 and blanket cylinders 933 provided in the off-set rotary press.
However, in the above method, in which the off-set rotary press is once stopped, the plate change operation which is carded out after stopping the press leads to a loss time. In addition, since the off-set rotary press is once stopped, restoration to the printing state requires a time. Therefore, the printing efficiency is inferior.
Further, since the off-set rotary press is once stopped, a great deal of paper loss is inevitable, thus increasing the printing cost.
In the above method, in which the in-printer 910 shown in FIG. 6 is connected, the plate change operation can be carried out without stopping the off-set rotary press 930. In this case, however, it is possible to obtain only single side printing.
The in-printer 910 is an exclusive priming machine for plate change printing of shop names or the like and has no other printing purpose. Therefore, it lacks versatility.
Moreover, since the printing plates of the individual printing cylinders 912 and 913 of the in-printer 910 are flexographic plates, equipment for producing flexographic plates is necessary, thus leading to added cost. Besides, the printing with the flexographic plate is inferior in quality to the printing with the off-set lithographic plate.
An object of the invention is to provide a continuously operative printing machine and a method of operating the same, which permit continuous plate change printing without stopping the printing machine, as well as permitting efficient high quality priming and also double-side printing.